1. Field of the Invention
The present invention relates to a captured image projection apparatus and a correction method for a captured image.
2. Description of the Related Art
Recently, projectors are used in presentations, meetings, etc. to expandingly project documents (characters and drawings, etc.) stored in personal computers on a screen. Projectors generally have a configuration for converting image information of documents obtained from personal computers, etc. into projection light by using an image conversion element such as liquid crystal, micro mirror array, etc.
In a case where a projector is used in a meeting, etc., in addition to the documents in the personal computer, written materials (newspapers, articles in magazines, presentation papers, written documents, etc.) one has on hand may need to be projected. In this case, since the written materials need to be digitalized (need to be converted into image data), image capturing of the written materials is done by using a so-called calligraphy/drawing camera. As the calligraphy/drawing camera, for example, one that has a configuration of a digital camera having a CCD and a MOS type image capture element is used.
In image-capturing the written materials using the calligraphy/drawing camera for digitalization, it is necessary to match the orientation of the paper and that of the calligraphy/drawing camera. For example, in image-capturing, if the camera is inclined, that is, if the center axis of the lens is not perpendicular to the written material, the resultant captured image is trapezoidally deformed and cannot be a rectangular image. A method of solving this problem is disclosed in, for example, Unexamined Japanese Patent Application KOKAI Publication No. 2002-354331 (FIG. 6). According to this method, in an image capturing apparatus in which a camera unit is supported by a support pillar on a document mounting, an angle detection sensor for detecting the inclination angle of the camera unit with respect to the document mounting is provided. By using the inclination angle detected by the angle detection sensor, the trapezoidal deformation in the captured image is corrected.
However, according to this method for correcting the captured image based only on the inclination angle of the camera unit, adjustment of the captured image before projection is limited to only correction of the trapezoidal deformation. For example, in image-capturing a written material for projecting the material on a screen, it is difficult to match the size, the orientation, etc. of the photo-object (written material) with the image range of the camera accurately. If correction other than correction for trapezoidal deformation is required as in this case, the above-described method cannot adjust the captured image.
Further, according to the above-described method, in a case where image-capturing of a large-sized written material is done without mounting the written material on the document mounting and by adjusting the orientation of the camera unit, if the written material is inclined, it is difficult to obtain the accurate inclination angle of the camera unit, i.e. the accurate image capturing angle with respect to the written material. Accordingly, in this case, there is a problem that trapezoidal deformation in the captured image cannot be properly corrected.